Door-lock device for household appliances, in particular for dishwashers

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Solution Overview

Problem

Existing door-lock devices for appliances, such as dishwashers, face issues with complexity, compactness, and reliability due to the need for a floating mechanism and helical springs under traction, which affect durability and efficiency.

Innovation Solution

A door-lock device featuring a support made of injection molded plastic with a lock wheel and retention elements, utilizing compression springs for enhanced reliability and a compact design, where the lock wheel rotates around a fixed axis with asymmetrical retention surfaces requiring different torques for locking and unlocking, eliminating the need for a bistable floating mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a floating mechanism and helical springs under traction are used to hold the lock element in set positions, then the lock element can maintain locking in open and closed positions, but the device complexity increases and the spring lifespan decreases

Engineering Contradiction:

Improvespring lifespanVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the floating mechanism and bistable positioning system from the door-lock device. The lock wheel is directly rotatable around a fixed axis without requiring complex floating supports or multiple springs to maintain position, thereby reducing component count while improving reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using traction springs that pull to hold positions, the patent employs compression springs that push against the lock wheel. This inversion of the spring mechanism eliminates the need for floating supports and reduces overall device complexity while maintaining reliable locking

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If a floating mechanism is used to rearrange the lock element after door opening, then the lock element can be repositioned, but the device complexity increases

Engineering Contradiction:

Improvelock element rearrangementVSAvoidnumber of components

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The lock wheel is designed to be freely rotatable around a fixed axis, allowing dynamic repositioning during door operation. The asymmetrical retention surfaces automatically guide the lock wheel through different angular positions as the door opens and closes, eliminating the need for floating mechanisms while maintaining ease of operation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The asymmetrical retention surfaces on the lock wheel work with the fixed-axis rotation to automatically rearrange the lock element during normal door operation. The mechanism uses the door's own movement to reposition the lock wheel, eliminating the need for separate floating rearrangement mechanisms

Inventive Principle:

Principle #25Self-service

3Reliability

If helical springs under traction are used to hold the lock element, then locking position is maintained, but the duration and reliability of operation decrease

Engineering Contradiction:

Improveoperation reliabilityVSAvoidspring duration

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent inverts the spring mechanism from traction (pulling) to compression (pushing). Compression springs are used to push the lock wheel into engagement with the door strike, which increases both the duration and reliability of operation by reducing stress on the spring components

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the mechanical parameters of the spring system by switching from traction to compression mode. This parameter change allows the springs to operate in a more favorable stress regime, extending their service life and improving overall operational reliability

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides a more compact, reliable, and efficient door-lock mechanism with reduced component count, improved spring lifespan, and balanced opening and closing forces, ensuring secure engagement and operation with lower maintenance needs.

Implementation Method 1

The retention elements cooperate with compression springs which press the retention elements against the lock wheel

Methodology Applied

Scientific EffectElastic force: Elasticity

Implementation Method 2

a lock wheel rotationally carried by the support around a fixed axis

Methodology Applied

Scientific EffectRotation:

Implementation Method 3

The locking arms can be engaged by a door strike in a locked position

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP3658729B1Door-lock device for household appliances, in particular for dishwashers

Publication Date: 2021.09.22 ILLINOIS TOOL WORKS INC

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AI summary

Door-lock device for appliances, in particular for dishwashers, comprising: - a support (12), - a lock wheel (34) rotationally carried by said support (12) around an axis of rotation (A), wherein the lock wheel (34) comprises a hub (36) and a plurality of locking arms (38) radially protruding from said hub (36), wherein said hub (36) comprises a plurality of retention surfaces (46), and - at least one retention element (48) elastically pressed into contact with said hub (36) to hold the lock wheel (34) in a plurality of locking positions.